3D Scanning and 3D Survey Make the Difference in Airport Glass Installation
What started as a standard 3D scanning, 3D survey, and modeling project ultimately required some traditional surveying expertise too.
The installation of 16 huge glass panes in the new air traffic control tower at the Cleveland Hopkins International Airport proved to be one of the most complex projects the PrecisionPoint team ever faced. Fortunately, Jay Scanlon PLS, our senior project manager, was there to make it happen.
Hunt Construction Group, a construction management firm in Indianapolis, won the contract to build the new 324-foot tall, $69 million air traffic control tower at the Cleveland airport.
The design of the tower ‘cab’ where the controllers sit and get a 360-degree view of the entire airfield called for installation of floor-to-ceiling glass panes. Each pane weight 1,600 pounds and leaned outward at the distinctive 30-degree tilt common at many airports.
A wrinkle in the plan, however, was that the trapezoidal panes had to fit perfectly together at their adjoining sides. This was due to a design that did not include center mullions. The precision in the window placements had to be within 1/16th inch.
Once the steal I-beams were set in place to form the frames for the windows, Hunt called in PrecisionPoint to perform a 3D survey and 3D scan of the installed steel structures.
Jay Scanlon went onsite with our new FARO Focus3D X330 scanner and captured 10 scans inside the tower cab. He returned to the office, registered the scans in FARO Scene and Autodesk ReCap and sent the point cloud to Hunt Construction.
Working in Revit and Navisworks, Hunt’s VDC Team linked the as-built point cloud in with the original design plans and compared the two.
As expected, some of the beams were not installed within the tolerances of the plans. Therefore, Hunt was able to determine from the 3D survey point cloud, which areas of the steel needed to be adjusted to fit the sills and glass.
Steel crews then moved the steel in those areas. The remaining alignment modifications would occur by shimming the aluminum sills that would attach the glass panes at their tops and bottoms to the steel. Dimensions for the shim packs were calculated from the as-built BIM and point cloud.
However, despite the 3D survey and 3D laser data used for the models, the glass installers continued to struggle in setting the panes.
“Hunt asked us to come back in and lay out the shims and sills,” said Jay Scanlon. “I brought in our reflectorless total station to survey in the sill angles.”
Subsequently, Scanlon took the 3D as-built BIM precisely created from the point cloud, into AutoCAD Civil 3D. He then calculated survey coordinates of all the angle points on the tops and bottoms of the sills.
Next, as the installers set the sills and shimmed them into place, Scanlon guided them in real time by shooting points with the total station. The installers made minute adjustments to the shim packs in response to his guidance, setting one frame after another until all 16 sill sets were perfectly aligned. Scanlon then re-scanned the cab to capture an as-built point cloud of the final location of the installed window sills.